The present disclosure relates to hydraulic systems, and more particularly to cushion mechanisms for hydraulic cylinders.
Hydraulic cylinders typically include a barrel and a reciprocable piston received within the barrel, and often also include a cushioning mechanism associated with the cylinder. The cushioning mechanism slows the travel of the piston when it nears the end of its stroke, preventing the piston from impacting the end of the barrel at a high speed. One type of cushioning mechanism includes a spear coupled to the piston, in which the spear enters a fluid outlet port of the cylinder as the piston approaches the end of its stroke. The action of the spear entering the port increases the fluid pressure acting against the piston as the piston travels to the end of the barrel, which slows down the piston. Such a configuration, however, may result in a pressure spike in the barrel as soon as the spear enters the port due to the increased flow resistance for hydraulic fluid exiting through the port. This rapid increase in pressure could damage the cylinder or the structure to which the cylinder is mounted. Although a relief valve may be used to mitigate the pressure spike associated with cushioning, adding a relief valve adds cost and complexity to the system.